Comprehensive detection of ctDNA variants at 0.1% allelic frequency using a broad targeted NGS panel for liquid biopsy research.

e23065Background: Advances in non-invasive tumor biomarker research have shown that tumor cells release fragments of DNA called circulating tumor DNA (ctDNA) into peripheral blood. Somatic mutations representing the tumors could be successfully detected from isolated ctDNA, providing new potential for tumor sample assessment in addition to traditional tissue biopsy methods. However, the low amount of ctDNA in the blood, which can be less than 1% allelic frequency, presents significant challenges for reliable variant detection with NGS assays. Improvement of sequencing accuracy at low allelic frequency is a critical factor in the implementation of NGS in ctDNA liquid biopsy research. Methods: We demonstrate the technical feasibility for a sample-to-variant NGS workflow that utilizes a broad multi-gene panel to survey a comprehensive list of variants relevant to multiple tumor types for liquid biopsy research. The method includes novel library preparation and analysis reporting for Ion Torrent™ sequencing p...